catena-Poly[[(1,10-phenanthroline)zinc]-μ-3-[3-(carboxylatomethoxy)phenyl]acrylato]

The asymmetric unit of the title compound, [Zn(C11H8O5)(C12H8N2)]n, is composed of a ZnII ion and 3-[3-(carboxylatomethoxy)phenyl]acrylate and 1,10-phenanthroline ligands. The ZnII ion adopts a distorted square-pyramidal ZnN2O3 coordination. The bridging mode of the dianion leads to the formation of zigzag chains parallel to [010]. Intermolecular π–π stacking interactions [centroid–centroid distance of 3.5716 (12) Å] lead to the formation of a two-dimensional network parallel to (001).


Comment
In recent decades, inorganic-organic hybrid materials such as coordination complexes have attracted plenty of attention (Fujita et al. (1994)) due to the fact that they might have potential applications as functional solid materials in adsorption, catalysis, and ion exchange (Comotti et al. (2008), Hong et al. (2006)), at the same time that they usually present intriguing topological structures (Moulton et al.(2001), Swiegers et al.(2000), Kaes et al.(2000)). Herein we report one such inorganic-organic hybrid compound, [Zn L (phen), where L is 3-carboxymethoxy phenyl acrylate (C 11 H 8 O 5 ) and phen is 1,10-phenanthroline(C 12 H 8 N 2 )].
As shown in Figure 1, the strucure contains one Zn II ion coordinated by two N atoms from a chelating phen and two O atoms from a chelating carboxylato group from one L ligand, defining the base of a distorted square pyramidal coordination; the apical site is occupied by a third O from the reamining carboxylato group of another L ligand which thus behaves in a µ 2 κ 3 bridging chelating mode, forming a one-dimensional zigzag chain which extends along the b axis ( Figure 2).
In this structure, the benzene ring from a L ligand and an adjacent six-membered heterocycle ring of phen are nearly parallel (dihedral angle: 4.83 (10)°), affording a face-to-face intermolecular π-π stacking with an intercentroid distance of 3.5716 (12) Å. Intermolecular π-π stacking interactions lead to the formation of a two-dimensional network ( Figure 3).

Experimental
A mixture of ZnCl 2 (0.136 g,1 mmol),3-carboxymethoxy phenycl acrylic acid(0.2220 g,1 mmol) and 1,10phenanthroline(0.0991 g,0.5 mmol) was dissolved in a 20 mL EtOH/H 2 O(v/v,1:9). Then, the pH value was adjusted to 7 through the use of a 2 mol/L NaOH solution. The mixture was then sealed in a 25 mL stainless steel reactor and heated to 433 K for 3 days. Then the reactant mixture was cooled to room temperature at the rate of 5 degrees per hour.
Evaporation of the resulting solution for a few days afforded colorless crystals of title compound.

Refinement
The carbon-bound H-atoms were positioned geometrically and included in the refinement using a riding model [C-H 0.93 Å U iso (H) = 1.2U eq (C)]. program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).  The molecular structure of the title compound. Displacement ellipsoids are drawn at the 50% probability level.

Figure 2
The one-dimensional chain structure in the title compound along the b axis.  View of the two-dimensional supramolecular network connected by π-π stacking interactions.  Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq